1. Field of the Invention
The present invention relates to a disc player capable of reproducing information from a disc-shaped recording medium such as a compact disc (“CD”). In particular, the invention relates to a disc player that is capable of reproducing information from a direct-read-after-write disc, such as a CD recordable disc (“CD-R”), when information is only partially recorded on the disc.
2. Description of the Related Art
In recent years, CD-Rs have become popular recording media for recording data and reproducing data. Typically, in a CD-R, recording tracks are formed with spiraling guide grooves, and the guide grooves are wobbled or snaked at particular frequencies of a carrier wave which has been frequency-modulated to correspond to absolute time information. For instance, when travelling along the recording tracks towards the outer circumference of the CD-R, the frequency of the guide grooves changes so that the absolute time information increases, and a specific position of a recording track contained in the CD-R can be determined by evaluating the frequency of the guide grooves at such position and determining the absolute time information. In some CD-Rs, the absolute time information is represented by absolute time in pre-groove (“ATIP”) data. By evaluating the guide grooves in a CD-R, a recording and/or reproducing apparatus is capable of performing a tracking control operation and controlling the spindle rotation of the CD-R.
In general, before any information is recorded on a CD-R, the CD-R is considered to be a blank disc. FIG. 5a shows an example of a cross-sectional view of a blank disc from the innermost position of the blank disc (i.e. a position close to the inner circumference of the disc) and an outermost diameter of the blank disc (i.e. a position close to the outer circumference of the disc). Also, after information is partially recorded on the CD-R, the CD-R is generally considered to be a partial disc. Furthermore, before all of the information is recorded on the partial disc, various information is not recorded at dedicated locations of the disc, and thus, the partial disc is not finally processed.
An example of a partial disc is shown in FIG. 5b. As shown in the figure, recorded information, such as music information, is partially recorded in a program area PA. Furthermore, while before all of the information is completely recorded on the disc, temporary table of contents (“TOC”) information is recorded in a program memory area PMA that is located between a lead-in area LIA of the disc and the innermost position of the disc. The temporary TOC information provides a recording history of the recorded information and typically contains a starting address and an ending address of the information that is recorded in the program area PA. Also, in the partial disc shown in FIG. 5b, no information is recorded in the lead-in area LIA or in the lead-out area LOA, and thus, the lead-in area LIA and the lead-out area LOA correspond to mirror surfaces.
After all of the information is completely recorded in the partial disc, the disc is finally processed via the recording apparatus (i.e. the disc is a finally processed disc). Specifically, the temporary TOC information contained in the program memory area PMA is recorded in the lead-in area LIA in a particular format, and a predetermined lead-out code identifying the lead-out area LOA is recorded in the lead-out area LOA. FIG. 5c shows the CD-R after it is finally processed, and as shown in FIG. 5d, the CD-R has substantially the same format as a digital audio CD (“CD-DA”). Therefore, an ordinary CD-DA reproducing apparatus can reproduce a CD-R that has been finally processed.
On the other hand, when a typical CD-DA reproducing apparatus (hereinafter referred to as a “CD reproducing apparatus”) attempts to reproduce a disc, the optical pickup is initially located in the lead-in area LIA of the disc. Thus, the CD reproducing apparatus cannot reproduce a partial disc because the temporary TOC information is recorded in the program memory area PMA, and the lead-in area LIA has a mirror surface and does not contain any information. Thus, when the CD reproducing apparatus initially positions the pickup in the lead-in area LIA, it cannot read the temporary TOC information, cannot perform a tracking control operation, and cannot control a spindle servo.
In order to attempt to overcome such problem, various CD reproducing apparatuses have been proposed that are capable of reproducing a partial disc. For example, in Japanese Unexamined Patent Publication No. Hei. 5-205272, the present assignee proposed a method for reproducing a partial disc with a CD reproducing apparatus. The operation of the CD reproducing apparatus will be briefly described below in conjunction with FIG. 6, which is a cross-sectional view of a partial disc.
As shown in FIG. 6, the CD reproducing apparatus performs an initial setup operation by placing an optical pickup at a home position H1 beneath the lead-in area LIA of the partial disc and attempts to read information from the lead-in area LIA. If the CD reproducing apparatus can reproduce information from the lead-in area LIA, the initial setup operation has been performed successfully, and the reproducing apparatus performs a subsequent operation. However, if the apparatus cannot reproduce information from the lead-in area LIA, the initial setup operation has not been performed successfully, and the controller of the CD reproducing apparatus instructs the pickup to move to a position H2 beneath the program area PA. Then, a second setup operation is performed in which the apparatus attempts to reproduce information from the program area PA. If information can be reproduced from such area PA, the second setup operation is performed successfully, and the reproducing apparatus performs a subsequent operation. However, if the second setup operation cannot reproduce information while the pickup 3 is located at the position H2, the second setup operation is not successful, and the pickup is returned to the position H1. Then, a third setup operation is performed to attempt to reproduce information from the lead-in area LIA. The above procedure is repeated for a substantial amount of time.
As described above, when the conventional CD reproducing apparatus attempts to reproduce a partial disc, a plurality of setup operations must be repeatedly performed to attempt to read information from various areas LIA and PA of the disc. Therefore, the conventional CD reproducing apparatus takes a long time to determine the type of disc that is loaded in the apparatus and takes a long time to determine whether or not it is capable of reproducing information from the disc.